With the alpha version 0.2.3.9 of Tor, the anonymity software, Tor clients can now connect to private bridges using IPv6. According to the announcement on the Tor blog, when using IPv6, bridges still need at least one IPv4 address, as they would otherwise lose contact with other nodes in the Tor network. On the Tor Developer mailing list, Linus Nordberg describes how to set the necessary options on a Tor bridge for IPv6 operation.

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You don't need to be a genius to debug a pf.conf firewall ruleset, you just need the guts to run tcpdump